Portal should allow opening a directory (integrated with GUI toolkits)

[mildred]

Linux distribution and version

Fedora Silverblue 29

Flatpak version

1.0.6

Description of the problem

Trying to open a network directory from the VLC flatpak on Flathub. The directory is in /run/user/1000/gvfs/sftp:host=.../.... The directory is not accessible.

When I choose to open a file instead of opening a directory, I get access to network storage.

Steps to reproduce

• Install VLC flatpak
• mount a network device on the host
• open VLC
• choose to open a file, navigate to /run/user/$UID/gvfs/... and you can see the network device all right
• choose to open a directory, navigate, and see that the network device is not available.

probably the first dialog is using an xdg portal, and not the second. Portals should be available and integrated in GUI toolkits just the same for single files and for opening directories.

[TingPing]

Duplicate of #200